about taps

jrkorman

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Jan 22, 2017
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Watched that this evening. As I am a bit new to this it was a bit of good info!
 

KMoffett

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After I bought spiral flute and spiral point taps, my old straight flute hand taps just sit on the shelf gathering dust.

Ken
 

projectnut

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Most of my taps (90+%) are either spiral point or spiral flute. About the only straight flute taps I have are those I either inherited, or those that were purchased when neither a spiral flute or spiral point were available.
 

WalterC

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I'm still waiting for first hand knowledge about the different coatings and applications.
 

macardoso

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My experience on coatings + research:

Bright Finish - Good for general purpose tapping, lower cost, especially good for aluminum. Most of my taps are bright finish.

Steam Oxide - Black porous surface finish. Rust resistant and seems to hold oil better through the cut, good for steel. A few of my higher end taps are steam oxide.

AlTiN - High wear resistance, good for tougher steels and cast iron, very bad for aluminum (aluminum in coating chemically binds to work). Common for high end endmills for steel cutting.

TiN - Gold coating, improved wear resistance over non-coated, can be used for aluminum. Higher lubricity than uncoated for slightly less tapping torque.

TiCN - High wear resistance, harder than TiN but cannot be used at high temp (not an issue for tapping usually)
 

pontiac428

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What type of coating is Kromedge, and what are it's strengths/weaknesses?
 

macardoso

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What type of coating is Kromedge, and what are it's strengths/weaknesses?
Looks to be a vintage Craftsman trademark for chrome plated taps. Higher surface hardness, but probably not as good as modern coatings.

EDIT: Looks like they lasted a while, but were not very sharp compared to a ground tap fresh out of the box (according to online reviews). They might have been chromed after grinding which could round a sharp cutting edge.
 
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